<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>天气案例_监视属性</title>
    <script type="text/javascript" src="../js/vue.js"></script>
</head>
<body>
       <div id ="root">
        <h2>今天天气很{{info}}</h2>
        <button @click="changeWeather">切换天气</button>
       </div>
</body>
      <script type="text/javascript">
        Vue.config.productionTip = false //阻止 vue 在启动时生成生产提示。

          const vm = new Vue({
               el:'#root',
               data:{
                isHot:true,
               },
               computed:{
                info(){
                    return this.isHot ? '炎热':'凉爽'
                }
               },
               methods:{
                changeWeather(){
                    this.isHot=!this.isHot
                }
               },
          })

          vm.$watch('isHot',{
            immediate:true,
            handler(newValue,oldValue){
                console.log('isHot被修改了',newValue,oldValue)
            }
          })
      </script>
</html>